DRAINAGE AREAS OF THE SKULL 145 



This similarity, in our opinion, is not only founded 

 upon, but is the outcome of, the operation of similar, or 

 related, developmental factors in the quasi-obliteration of 

 the continuity of the lumen of the neuro-enteric canal, 

 and in the laying down, in the interpolated metamorphic 

 structures, of a drainage system, by which the separated 

 and differentiated portions of that canal are maintained in 

 modified histological continuity, but altered functional role. 

 In our observations and studies bearing on this system of 

 drainage we have been much impressed by the histological 

 and physiological sameness involved in the processes of 

 the early embryonic development, separation, and differen- 

 tiation of the two divisions of the neuro-enteric canal, as 

 well as by the continuance in after life, on somewhat 

 corresponding lines, of some of their common character- 

 istics, structural and functional. Thus the " lymphoid " 

 element is largely in evidence in the textural arrangements 

 of the nasal, pharyngeal, and anal, metamorphic, or 



FIG. 60. VIEW OF THE CEREBRO-SPINAL AXIS. (After Bourgery.) i. 



The right half of the cranium and trunk of the body has been removed by a vertical 

 section ; the membranes of the right side of the brain and spinal cord have been 

 cleared away, and the roots and first part of the fifth and ninth cranial nerves, and 

 of all the spinal nerves of the right side, have been dissected out and laid sepa- 

 rately on the wall of the skull and on the several vertebrae opposite to the place 

 of their natural exit from the cranio-spinal cavity. 



F, T, O, cerebrum ; C, cerebellum ; P, pons Varolii ; mo, medulla oblongata ; 

 in s, m s, point to the upper and lower extremities of the spinal marrow; c e, on 

 the last lumbar vertebral spine, marks the cauda equina ; v, the three principal 

 branches of the nervus trigeminus ; C i, the sub-occipital or first cervical nerve ; 

 Cvni, the eighth or lowe-t cervical nerve; D r, the first dorsal nerve; D xn, 

 the last dorsal ; L, I, the first lumbar nerve ; L v, the last lumbar ; S I, the first 

 sacral nerve ; S v, the fifth ; Co i, the coccygeal nerve ; s, the left sacral plexus. 1 



1 The relation between the bodies and spines of the vertebrae and the places of 

 attachment of the nerve-roots to the cord is also illustrated by this figure. For 

 more detailed information on this point the reader may consult Gowers, The 

 Diagnosis of Diseases of the Spinal Cord, 1880. 



FIG. 61. ANTERIOR AND POSTERIOR VIEWS OF THE MEDULLA OBLON- 

 GATA AND SPINAL CORD WITH SECTIONS. (Allen Thomson. ) \. 



The cord has been divested of its membranes and of the roots of the nerves. A is an 

 anterior, B a posterior view. In these figures the filiform prolongation, repre- 

 sented separately in B', has been removed ; C shows a transverse section through 

 the middle of the medulla oblongata ; D, a section through the middle of the 

 cervical enlargement of the cord ; E, through the upper dorsal region ; F, through 

 the lower ; G, through the middle of the lumbar enlargement ; and H, near the 

 lower end of the conus medullaris. 



i to 6 refer to parts of the medulla oblongata ; the remaining numbers to parts 

 of the spinal cord. 



i, pyramids ; i', their decussation ; 2, olivary bodies ; 3, lateral columns ; 4, 

 posterior surface of the medulla oblongata ; 4', calamus scriptorius ; 5, funiculus 

 gracilis ; 6, posterior lateral columns passing to the side ; 7, 7, anterior median 

 fissure of the spinal cord ; 8, 8, antero-lateral impression corresponding to the 

 attachments of the anterior nerve roots ; g, 9, posterior median fissure ; 10, 10, 

 postero-lateral groove; X, tapering extremity of the cord; X, X , in B', filum 

 terminate. 



K 



